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Old 12-18-2016, 12:58 AM   #37 (permalink)
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Originally Posted by jamesqf View Post
Heat = wasted energy, no? Which kinda tanks the efficiency of your EV. Also, cooling the battery pack should not, with proper design, necessitate running the A/C to cool the passenger cabin.
If you're looking at overall efficiency, yes. Charging more slowly is more efficient from an energy-only perspective. The AC compressor is shared between the battery cooling system and the cabin on my vehicles. That doesn't mean the cabin is being cooled while the battery is cooled. On the contrary, when charging in 110F+ temperatures this summer, cabin cooling was significantly limited when I returned the car. The trade-off here is fast charging = convenience on trips. And having the pack temperature managed is paramount to longevity.

There's also the matter of range. You'd rather pre-cool your cabin on shore power than when you're on pure battery, at least if you've got a long haul ahead of you. That's less important than pre-heating the pack and the cabin, which obviously takes much more energy.

Originally Posted by jamesqf View Post
Not as much unnecessary consumption as keeping the A/C running for the whole time the car's charging. Of course a roof or other sunshade helps. So does leaving the windows open.
Again, while the cabin fans aren't running and cooling the cabin, the compressor is indeed necessary for pack stability. A shaded spot is much more efficient for the vehicle and the cabin. If it has PV on it, fine. My argument was that the shade is beneficial. Hopefully I've been clearer.
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